London has been battered by 50mph winds that have felled trees and caused travel chaos. Powerful gusts swept across the capital as the Met Office issued a yellow "be aware" weather alert for most of the country.

An SAS sniper jailed for illegally possessing a pistol and ammunition has thanked the "great British public" after winning an appeal and walking free.

Father-of-two Sgt Danny Nightingale, 37, who lives near Crewe, Cheshire, said he had been "humbled" by public reaction to his plight.

He had been sentenced to 18 months' military detention earlier this month by a judge sitting in a military court after admitting illegally possessing a Glock 9mm pistol and more than 300 rounds of ammunition.

But three appeal judges concluded the sentence was too harsh following a hearing at the Court Martial Appeal Court in London on Thursday. They cut the term to 12 months, said it should be suspended - and ordered Sgt Nightingale's release. Judges heard that more than 100,000 people signed a petition calling for Sgt Nightingale to be freed after his wife Sally, 38, and other family members launched a campaign.

And Sgt Nightingale said the level of public support had been "humbling" as he hugged Mrs Nightingale after being released. "Thank you to the great British public," he said. "They have been absolutely wonderful in their support. It has just been extremely humbling. Very, very humbling." Mrs Nightingale said: "It can only be good for all the troops out there fighting for our country to see justice has been done."

Defence Secretary Philip Hammond said: "I am delighted for Sgt Nightingale and his family that he will be home not only before Christmas as they'd hoped, but by the end of November. The justice system has worked. I was pleased that an appeal was heard quickly and it is right that a court should decide on whether the sentence was appropriate. The Court of Appeal has decided the sentence was too harsh and has freed him."

Judges heard that the gun had been a gift from Iraqi special forces soldiers Sgt Nightingale had trained. They were told that Sgt Nightingale planned to have the weapon decommissioned and keep it as a trophy. And they heard that Sgt Nightingale, who has suffered medical problems affecting his memory, appeared to have put the gun in a cupboard in his Army accommodation in Hereford on a "very hectic day" when preparing to deploy to Afghanistan. Sgt Nightingale, whose accommodation was not on the SAS base at Hereford, said he had not "appreciated" that he had the weapon.

Lawyers representing Sgt Nightingale accepted that he had admitted "serious offences" which crossed the "custody threshold". But they asked three appeal judges - the Lord Chief Justice, Lord Judge, Mr Justice Fulford and Mr Justice Bean - to "temper justice with mercy". Lieutenant Colonel Richard Williams, a former SAS commander, gave Sgt Williams a character reference - and told judges that the sniper had put his life at risk on many occasions and "stood out" amongst special forces colleagues.

Lord Judge - the most senior judge in England and Wales - said the appeal panel had concluded that the case involved an exceptional person and exceptional circumstances and that the sentence could be reduced. Judges said they would rule later on whether Sgt Nightingale's convictions should be overturned.

The judge who sentenced Sgt Nightingale following the court martial in Bulford, Wiltshire, on November 7 said the sniper may still have a future in the Army. "We have not dismissed you or reduced you in rank," said Judge Alastair McGrigor, who sat with a panel of Army officers. "We consider that you may still, with your specialist experience, be of use to the Army in the future." Sgt Nightingale said that he could not answer questions about his future.